In Kingdom Hearts II, there is a secret ending movie that you can unlock once completely certain requirements, since there are three modes or levels of diffculty, you need to know which mode you chose, therefore which mode you can allow.

Beginner Mode : Cannot Unlock (Impossible).
Standard Mode : Complete All Aspects Of Jimminy's Journal.
Proud Mode : Complete All Worlds, 100 Acre Wood and Atlantica Inculded.